The present invention relates to saving power in a physical storage device of a storage system.
A storage system comprising a plurality of physical storage devices is known. This type of storage system, for example, includes a disk array apparatus comprising a plurality of disk devices (for example, hard disk drives) in an array. As technology related to saving power in a disk array apparatus, for example, there is the technology disclosed in Japanese Patent Laid-open No. 2000-293314, which is referred to here as Literature 1. According to Literature 1, a disk array apparatus controls the power saving of a disk device (selects power ON/OFF or a power-saving mode) subsequent to the passage of a predetermined period of time during which there has not been an access from an upper-level device. Further, when there is an access from an upper-level device, if the power to the access destination disk device is OFF, the disk array apparatus executes the access subsequent to turning ON the power to this disk device.
For example, a person might want to save power in a desired storage device. One method for realizing this could be such that a power-saving indication, which specifies a user-desired storage device, is sent to a storage system from an upper-level computer, and, in accordance with this power-saving indication, the storage system specifies one or more physical storage devices of the storage device specified by this power-saving indication, and subjects this one or more physical storage devices to power savings. An upper-level computer, for example, can include a physical host computer, a virtual host computer provided on either one or a plurality of host computers, and an application.
However, a storage device of a storage system can be a storage device that is shared by a plurality of upper-level computers. If one or more physical storage devices of such a storage device are subjected to power savings in accordance with a power-saving indication from a certain upper-level computer of a plurality of upper-level computers, when another upper-level computer of this plurality of upper-level computers is either in the process of using or is about to use this storage device, processing to cancel power saving must be performed separately in order to utilize this storage device.